1. Field of the Invention
The present invention relates to an electrical, cable which has, or consists of at least two strands, and an outer casing placed on the inner casing, as well as a manufacturing method for the cable according to the invention. The electrical cable according to the invention includes an inner and an outer casing which can be easily removed from the strands for removing the casing section by section.
In particular, the invention relates to cables in which the outer casing is placed directly on the inner casing without being integrally connected, or in which the outer casing is fixedly connected to the inner casing, preferably be a glued connection or an integral connection.
For preparing the cables for assembly, for example, the connection of contact elements to the electrical conductors, which form the strands together with insulation, it is required to completely remove the layers in one end section of the cable which surround the strands. Up to now it is necessary to completely radially sever the inner casing and the outer casing in order to be able to remove an adjacent section from the strands.
In the cable according to the invention, the inner casing and the outer casing each consist of a polymer mixture whose polymer component includes or consists of a thermoplastic elastomer. The thermoplastic elastomer is in particular thermoplastic polyurethane (TPU) which is, for example, a block copolymer in which soft segments of polyol with diisocyanate alternate with hard segments of diisocyanate with a short chain diol. Preferred thermoplastic polyurethane polymers are available under the name Ellastolan from the company ESAF.
2. Description of Related Art
It is known to manufacture cables with at least two strands and a casing of polyurethane surrounding the strands.
US 2008/0283272 A1 describes a cable whose strands are surrounded by foam which is compressed by an outer layer. A woven material of encased wire is used as the outer layer which generates the pressure acting on the foam.
DE 2025026 describes a cable around which is wound a web-like insulation material composed of a layer of polyurethane foam between two foils. A screening layer of aluminum strip is additionally placed on this winding and an outer casing of polyethylene is placed thereabove.
EP 1176613A2 describes a sample mixture for an inner casing of 50% polyether urethane as base material, 20% polyolefin, 29% calcium carbonate, and 1% propellant, on which is placed an outer layer. In this connection, the outer layer may be composed of the same base material as is also contained in the foamed mixture. However, the inner layer still has additives, which, in the example, are polyolefin and calcium carbonate.